It is known that color developers containing an aromatic primary amine developing agent autoxidize when they come in contact with air (T. H. James, The Theory of the Photographic Process, 4th edition, p. 315 (1979)). As a result the color developer turns dark brown, and further a black tarry contaminant is produced. This black tarry contaminant will stick to the photographic material and become stain after the processing, or it will stick to processor parts in contact with the color developer, such as the processing solution tank, pipelines, and conveying rollers, and will stain heavily the processor when continuous processing is carried out in an automatic processor by supplying the developer. In particular, when parts that come in contact with the photographic material are stained, the stain will be transferred to the photographic material and the commercial value of the photographic material will be lost.
Recently, it has become practiced that color photographic material is subjected to color processing in a short period of time, up to 5 min, under high temperature conditions of 30.degree. C. or higher. This high-temperature color developer is apt to be oxidized by air and is liable to produce the above tarry contaminant. Further, in the field of development processing of color negative film and color paper, development processing using small-sized automatic processors called "mini-labs" is becoming prevalent very quickly. In the "mini-lab" processing, since the processing amount per day is small, the time of the color developer staying in the color developer tank becomes longer and the color developer is in such a state that it is liable to be oxidized by air.
As means of preventing air oxidation of color developers, techniques wherein a compound called a preservative is added to the color developer have been practiced. As preservatives, conventionally compounds such as sulfites and hydroxylamine salts are known (L. F. A. Mason, Photographic Processing Chemistry, p. 34 (1966)).
In particular, sulfites are remarkably effective in preventing the coloring of the color developer and the occurrence of a tarry contaminant. However, it is known that, for the high-silver-chloride color photographic materials used recently in quick development processing, it is practically difficult to use sulfites that highly block color formation and highly solubilize silver.
To perform quick development processing and low-replenishment processing wherein a high-silver-chloride photographic material is used, many preservatives in place of sulfites and hydroxylamine salts have been studied. For example, International Publication Patent No. WO 87-04534 discloses a method wherein alkyl-substituted hydroxylamines are used, and JP-A ("JP-A" means unexamined published Japanese patent application) Nos. 170642/1988 and 146041/1988 disclose a method wherein hydrazines and hydrazides are used as preservatives.
It is also known that many compounds known as chelating agents of metal ions have been shown to play an important role in the preservation of developers (Research Disclosure No. 17048, June 1978), and they can be used together with the above preservatives.
Although all of the above compounds have a high effect for suppressing air oxidation of color developers and for keeping photographic performance, they cannot suppress air oxidation completely, which results in the formation of a tarry contaminant that causes various injurious problems. In particular, in low-replenishment processing, since the periods of a color developer and a color developer replenisher staying in the tanks are longer and the pH and the concentration of the developing agent of the color developer replenisher are high, they are in a state liable to be oxidized by air, and therefore development of techniques is desired wherein formation of the above tarry contaminant in color developing agents is prevented or the influence of the contaminant is made unharmful.